This invention relates in general to preventing the production of particulate materials through a wellbore traversing an unconsolidated or loosely consolidated subterranean formation and, in particular, to a gravel packing apparatus having an integrated joint connection and a method for use of the same.
Without limiting the scope of the present invention, its background is described with reference to the production of hydrocarbons through a wellbore traversing an unconsolidated or loosely consolidated formation, as an example.
It is well known in the subterranean well drilling and completion art that particulate materials such as sand may be produced during the production of hydrocarbons from a well traversing an unconsolidated or loosely consolidated subterranean formation. Numerous problems may occur as a result of the production of such particulate. For example, the particulate causes abrasive wear to components within the well, such as the tubing, pumps and valves. In addition, the particulate may partially or fully clog the well creating the need for an expensive workover. Also, if the particulate matter is produced to the surface, it must be removed from the hydrocarbon fluids by processing equipment at the surface.
One method for preventing the production of such particulate material to the surface is gravel packing the well adjacent the unconsolidated or loosely consolidated production interval. In a typical gravel pack completion, a sand control screen is lowered into the wellbore on a work string to a position proximate the desired production interval. A fluid slurry including a liquid carrier and a particulate material known as gravel is then pumped down the work string and into the well annulus formed between the sand control screen and the perforated well casing or open hole production zone.
The liquid carrier either flows into the formation or returns to the surface by flowing through the sand control screen or both. In either case, the gravel is deposited around the sand control screen to form a gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the particulate carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of particulate materials from the formation.
It has been found, however, that a complete gravel pack of the desired production interval is difficult to achieve particularly in long or inclined/horizontal production intervals. These incomplete packs are commonly a result of the liquid carrier entering a permeable portion of the production interval causing the gravel to form a sand bridge in the annulus. Thereafter, the sand bridge prevents the slurry from flowing to the remainder of the annulus which, in turn, prevents the placement of sufficient gravel in the remainder of the annulus.
Prior art devices and methods have been developed which attempt to overcome this sand bridge problem. For example, attempts have been made to use devices having perforated shunt tubes or bypass conduits that extend along the length of the sand control screen to provide an alternate path for the fluid slurry around the sand bridge. It has been found, however, that shunt tubes installed on the exterior of sand control screens are susceptible to damage during installation and may fail during a gravel pack operation. In addition, it has been found that it is difficult and time consuming to make all of the necessary fluid connections between the numerous joints of shunt tubes required for typical production intervals. Moreover, it has been found that the velocity of the fluid slurry may decrease below the settling velocity of the fluid slurry in transition sections that allow mixing of the flow streams from multiple shunt tubes such that the gravel drops out of the fluid slurry and clogs the transition section preventing further flow therethrough.
Therefore a need has arisen for an apparatus and method for gravel packing a production interval traversed by a wellbore that overcomes the problems created by sand bridges. A need has also arisen for such an apparatus that is not susceptible to damage during installation. Further, a need has arisen for such an apparatus that is not difficult or time consuming to assemble. Moreover, a need has arisen for such an apparatus that maintains sufficient velocity of the fluid slurry in transition sections.
The present invention disclosed herein comprises a gravel packing apparatus and method for gravel packing a production interval of a wellbore that traverses an unconsolidated or loosely consolidated formation that overcomes the problems created by the development of a sand bridge between a sand control screen and the wellbore. Importantly, the gravel packing apparatus of the present invention is not susceptible to damage during installation or failure during use and is not difficult or time consuming to assemble.
The gravel packing apparatus of the present invention comprises an outer tubular forming a first annulus with the wellbore and a sand control screen disposed within the outer tubular forming a second annulus therebetween. The outer tubular includes a plurality of openings that allow for the production of fluids therethrough and plurality of outlets that allow the distribution of a fluid slurry containing gravel therethrough.
In the volume within the second annulus between the sand control screen and the outer tubular there are one or more channels that define axially extending slurry passageways with sheet members positioned between the channels and the sand control screen. The sheet members create a barrier to the flow of fluids between the channels and the sand control screen. The volume within the second annulus between adjacent channels forms axially extending production pathways. The channels prevent fluid communication between the production pathways and the slurry passageways. In addition, transition members at either end of each joint of the gravel packing apparatus of the present invention define the axial boundaries of the production pathways.
As such, when a fluid slurry containing gravel is injected through the slurry passageways, the fluid slurry exits the slurry passageways through outlets in the channels and the outer tubular leaving a first portion of the gravel in the first annulus. Thereafter, the fluid slurry enters the openings in the outer tubular leaving a second portion of the gravel in the production pathways. Thus, when formation fluids are produced, the formation fluids travel radially through the production pathways by entering the openings in the outer tubular and exiting the production pathways through the sand control screen. The formation fluids pass through the first portion of the gravel in the first annulus prior to entry into the production pathways, which contains the second portion of the gravel, both of which filter out the particulate materials in the formation fluids. Formation fluids are prevented, however, from traveling radially through the slurry passageways as the sheet members prevent such flow.
In a typical gravel packing operation using the gravel packing apparatus of the present invention, the first annulus between the outer tubular and the wellbore may serve as a primary path for delivery of a fluid slurry. This region serves as the primary path as it provides the path of least resistance to the flow of the fluid slurry. When the primary path becomes blocked by sand bridge formation, the production pathways of the present invention serves as a secondary path for delivery of the fluid slurry. The production pathways serve as the secondary path as they provide the path of second least resistance to the flow of the fluid slurry. When the primary and secondary paths become blocked by sand bridge formation, the slurry passageways serve as a tertiary path for delivery of the fluid slurry. The slurry passageways serve as the tertiary path as they provide the path of greatest resistance to the flow of the fluid slurry but are least likely to have sand bridge formation therein due to the high velocity of the fluid slurry flowing therethrough and their substantial isolation from the formation.
Commonly, more than one joint of the gravel packing apparatus must be coupled together to achieve a length sufficient to gravel pack an entire production interval. In such cases, multiple joints of the gravel packing apparatus of the present invention are coupled together via a single threaded connection between two outer tubulars of adjacent joints such that an integrated joint connection is formed wherein the slurry passageways of the various joints are in fluid communication with one another allowing an injected fluid slurry to flow from one such joint to the next.
More specifically, the integrated joint connection includes a lower end transition member of an upper joint positioned proximate an upper end transition member of a lower joint. In this configuration, when the fluid slurry is traveling from the slurry passageway of the upper joint to the slurry passageway of the lower joint, the fluid slurry travels from the exterior to the interior of the lower end transition member of the upper joint then from the interior to the exterior of the upper end transition member of the lower joint.
In another aspect, the present invention involves a method for gravel packing an interval of a wellbore that includes providing a gravel packing apparatus having a plurality of joints each including an outer tubular positioned around a sand control screen assembly forming a screen annulus therebetween including an axially extending slurry passageway and first and second transition members disposed at opposite ends of each joint, connecting first and second joints such that the second transition member of the first joint is proximate the first transition member of the second joint, locating a gravel packing apparatus within the interval of the wellbore forming a wellbore annulus, injecting a fluid slurry into the slurry passageway of the first joint such that a first portion of the fluid slurry exits the slurry passageway into the wellbore annulus and such that a second portion of the fluid slurry travels from the slurry passageway of the first joint to the slurry passageway of the second joint by traveling from the exterior to the interior of the second transition member of the first joint then from the interior to the exterior of the first transition member of the second joint and terminating the injecting when the wellbore annulus is substantially completely packed with the gravel.